Typically, agricultural machines and implements are towed by a tractor. As is also typical of agricultural implements, the implements are generally powered from the tractor utilizing the tractor's power takeoff output shaft, i.e., a spline in the rear of the tractor, driven by a driving means such as a mechanical connection to the tractor's transmission or powered by the tractor's hydraulic pump. The transfer of power from the tractor's PTO spline, to the driven means, i.e., the agricultural implement is accomplished by means of a PTO drive shaft. Typically, the driving spline on the tractor includes a small, circumferential detent positioned from about 1 to about 2 inches from the exposed end. This detent allows the drive shaft to be removably captured on the spline, as detailed below.
The PTO drive shaft typically includes: a main front portion adapted to be connected to the tractor PTO output shaft; a rear or aft portion that is connected to a corresponding driving spline or shaft of the implement; and a middle portion that typically is telescopically adjustable so the length of the drive shaft can be adjusted over a predetermined distance or range to facilitate connecting or disconnecting the PTO drive shaft to/from tractor as well as allowing the drive shaft to adjust during use, as when the distance between the tractor and the implement is varied over terrain or during turns and the like.
The PTO drive shaft is connected to the tractor PTO output shaft utilizing a PTO hookup assembly. The PTO hookup assembly may have a single universal joint (U-joint) having a portion of the U-joint captured between a first yoke being rigidly affixed to the drive shaft and a another portion captured between a second, forward (toward the tractor) yoke. The second yoke conventionally includes an internally splined member that slips over and is mateable with the externally splined tractor PTO output shaft.
The second yoke includes a means for capturing the spline so that it will not slip off. Such capturing means can be a spring-assisted collar that circumferentially encircles the outer portion of the second yoke, proximate the end closest to the tractor. To mate the second yoke to the tractor's driving spline, the collar is pulled rearward, toward the implement, and the yoke slipped over the spline. When properly seated, the collar moves forward over the circumferential detent of the spline to a home position preventing the yoke from receding or pulling free from the spline. Alternatively, the capturing means can be a spring loaded button or pin that must be pushed inward to mate the second yoke to the tractor's driving spline. When properly seated the button or pin moves forward over the circumferential detent of the spline to its home position preventing the yoke from receding or pulling free from the spline. Both of these capturing means are well known in the art.
Alternatively, the drive shaft may include a plurality of universal joints adjacent the forward and rearward ends, respectively, of the hookup assembly to form a constant velocity (CV) joint. The CV joint accommodates pivoting movement between the tractor and the towed implement that may occur during use. In the drive shaft extending rearwardly from the PTO, a constant velocity (CV) joint conventionally is attached to the PTO shaft at the back of the tractor, and the drive shaft extends rearwardly from the CV joint to connect with the driven shaft on the farm equipment. The CV joint maintains a constant instantaneous rotational velocity of the drive shaft, throughout each complete revolution of the PTO shaft, whether or not the tractor is turning relative to the towed equipment.
Over the years, implements and agricultural equipment for tillage, cultivation and other agricultural operations have been developed with the objectives of increasing efficiency and lowering operating costs. Modern agricultural operations commonly require equipment be adapted for transporting over public roads. For example, many farmers and farming operations work multiple, noncontiguous fields with the same equipment, which must be configured to comply with traffic regulations, including maximum width requirements. Various implement transport mechanisms have been developed for this purpose. For example, implements are commonly designed to fold and unfold between field use and transport configurations.
It is important to be able to move these heavy agricultural implements from one location to another and to quickly connect and disconnect the equipment. One method of transport employs the use of a trailer having a lift mechanism as described in U.S. Pat. No. 6,238,170, which describes an implement transporter including a trailer having a lifting and rotating mechanism for engaging, lifting and rotating the implement. The trailer includes a turntable supporting a cantilevered arm and the cantilevered arm includes a lift and support assembly. However, such methods are time consuming and require the added expense of obtaining a trailer as well as an appropriate vehicle for pulling the trailer.
A great number of mechanical agricultural implements typically connect to transportation devices, such as a half or one ton truck using a hitch, such as Cat. II or Cat. III two-point hitch, or utilize a removable drawbar type hitch. There are several classes or variations of the trailer hitch receiver, most hitch receivers are bolted to the chassis of the towing vehicle. The receiver recess or opening varies in size and configuration to meet the tongue load and other weight limitations. For example, one of the more common constructions is a Cat. III hitch receiver. The receiver has a 2-inch by 2-inch inside dimension (ID) opening that is designed to removably mate with the hitch member having a slightly smaller outside dimension. Many trucks and sport utility vehicles are fitted with such a Class III or IV trailer hitch. The Class of this type of hitch receiver is generally indicative of the weight capacity of the hitch and the receiver size. There are several additional classes, such as Class I or Class V, trailer hitches available, depending on the application and desired weight carrying capacity. The receiver has two coaxially aligned holes or apertures on the sides that are used to align with a corresponding channel in the hitch so a retaining pin can be inserted to capture the hitch when properly inserted into the hitch receiver recess.
As known in the art, a hitch includes a hole on one end for mounting a means for connecting the towed device to the towing vehicle. Examples would be a trailer ball having an appropriate diameter or using a hitch pin through an implement yoke and the hole. Such mounting means permits the towed device to be pivotally secured to the hitch. In the case of a ball mount, it also comes in multiple dimensions to make it adaptable which is known in the art.
A problem with the present arrangement is that the PTO drive shaft is normally not supported except by its connections to the rear universal joint on the implement driven spline and to the tractor's driving spline. When the implement PTO drive shaft is separated from the tractor for transport, whether over ground or on the road, the forward end of the hookup assembly is free to dangle. Since the PTO drive shaft is typically telescopic, the free end has the potential to be exposed to the mud as well as damage if the hookup assembly end drops off or slips forward sufficiently to contact the ground or a paved surface.
Up to now, the PTO drive shaft was either tied to a portion of the implement for transport or was removed altogether. This is a problem for larger agricultural implements, such as hay bailers, hay tedders, sprayers, spreaders, seed drills, and large rotary cutters, since the PTO drive shafts are typically long, heavy and cumbersome if removed from the implement. In such cases the PTO drive shaft must be secured separately to prevent loss. Moreover, if the PTO drive shaft is retained on the implement and the free end slips forward of otherwise breaks free the forward end could be damaged due to contact with the ground, and/or the implement may be damaged as well as pose a road hazard if it is dropped on the road. Additionally, many of these PTO drive shafts are quite expense if needed to be replaced.
Accordingly, there is a need for a device that would allow an implement that utilizes a PTO drive shaft for power to have a portion, and desirably, the driving portion of the PTO drive shaft removably attached during transport to a hitch on a transporting vehicle. It would further be advantageous for the connection to allow the PTO drive shaft to rotate if necessary.